1. Field
The present invention relates generally to wireless communications, and more specifically, to communication systems for multicasting/broadcasting information to multiple users.
2. Background
Broadcast, or multicast services, refer to a communication system used to transmit information from a transmitter to multiple receivers or users. Examples of multicast/broadcast, or point-to-multipoint communication systems, include dispatch systems, such as used by police, trucking companies, and taxi companies where a central dispatcher broadcast signals to one or more vehicles. The signal may be directed to a specific vehicle or to all vehicles simultaneously.
As mobile radio networks have become commonplace, such as cellular telephone networks, customers have begun to desire to receive broadcast and multicast services such as video, multimedia, and Internet Protocol (IP) over a wireless communication link. For example, customers desire to be able to receive streaming video, such as television broadcast, on their cell phone or other portable wireless communication device. Other examples of the type of data that customers desire to receive with their wireless communication device include multimedia multicast/broadcast and Internet access.
Wireless communication systems have many applications including, for example, cellular telephones, paging, wireless local loops, personal digital assistants (PDAs), Internet telephony, and satellite communication systems. A particularly important application is cellular telephone systems for mobile subscribers. As used herein, the term “cellular” system encompasses both cellular and personal communications services (PCS) frequencies. Various over-the-air interfaces have been developed for such cellular telephone systems including frequency division multiple access (FDMA), time division multiple access (TDMA), and code division multiple access (CDMA).
Different domestic and international standards have been established to support the various air interfaces including, for example, Advanced Mobile Phone Service (AMPS), Global System for Mobile (GSM), General Packet Radio Service (GPRS), Enhanced Data GSM Environment (EDGE), Interim Standard 95 (IS-95) and its derivatives, IS-95A, IS-95B, ANSI J-STD-008 (often referred to collectively herein as IS-95), and proposed high-data-rate systems such as wideband CDMA (WCDMA). These standards are promulgated by the Telecommunication Industry Association (TIA), 3rd Generation partnership Project (3GPP) and other well-known standards bodies.
Broadcast techniques for use in the various air interfaces are also beginning to become standardized. One type of multicast/broadcast in wireless communication systems that is beginning to become standardized is Multicast Broadcast Multimedia Service (MBMS) in the 3GPP. A goal of MBMS in 3GPP is to provide a medium to high speed service to multiple users in a radio-efficient way. Different versions of MBMS are being developed and standardized for at least two air interfaces, WCDMA and GSM/GPRS/EDGE.
Continuing advancements in wireless communication devices result in newer devices having enhanced capabilities. As new wireless communication devices with enhanced capabilities are introduced to the market it is common for users with devices of varying capability to desire receiving the same MBMS, or at least similar versions of the same MBMS, according to the capabilities of the respective devices.
In a parallel fashion, users in different locations will experience different radio impairments. It is also common for users with different reception qualities to desire receiving the same MBMS, or at least similar versions of the same MBMS, according to those reception qualities.
There is therefore a need in the art for a technique enabling wireless communication devices with different capabilities, or experiencing different reception qualities, to receive similar versions of the same MBMS, corresponding to those capabilities.